The present disclosure relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present disclosure relates to collapsible prosthetic transcatheter heart valves that are easier to load into a delivery device and that minimize or reduce paravalvular leaks.
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two common types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To load such valves into a delivery apparatus and deliver them into a patient, the valve is first collapsed or crimped to reduce its circumferential size.
When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as a sheath covering the valve is withdrawn.
After implantation, imperfect sealing between the prosthetic valve and the native tissue at the site of implantation may cause complications such as paravalvular leakage (“PV leak”) in which retrograde blood flows through one or more gaps formed between the structure of the implanted valve and cardiac tissue as a result of the imperfect sealing.